chpp is a preprocessor. Therefore, its main purpose is to modify
input text by including other input files and by macro expansion.
Programs performing these tasks already exist, among them the popular C
Preprocessor (cpp) and m4, which have proven to be
convenient and valuable tools suitable for a variety of tasks. The
motivation for chpp is thus questionable.
What distinguishes chpp from at least the two programs mentioned
above are mainly two features:
chpp is non-intrusive. This means that you can take your
favourite text and it is very unlikely that it will be changed when
piped through chpp. Due to this feature it is pretty easy to
start using chpp since you can just start writing your text and
need not concern yourself with chpp sitting in the background
changing it for no obvious reason.
chpp is not just a package for performing simple macro expansion,
but can indeed be considered a full-fledged programming language. Most
importantly, it provides support for complex data structures, namely
lists and hashes (associative arrays), which can be nested arbitrarily.
chpp consists of two parts which could, in some sense, be seen as
two separate passes over the input file. This is not entirely true,
though, since the two parts are intertwined and cannot be separated. The
first part, which performs command processing, is similar to what
cpp does. It allows the inclusion of other files, simple macro
definitions and conditional inclusion and exclusion of parts of the
input. The second part does macro processing and is the actual workhorse
and core of chpp.
Although macro processing on its own could do anything that can be accomplished with commands, the latter are not only easier to use but also easier to read and therefore improve clarity.
chpp stands for
chpp does not stand for Chakotay Preprocessor.
chpp
chpp can be used very well as
chpp (see section The History of chpp).
chpp will become even more attractive
for this kind of application when the planned database interface
(see section Planned but not yet Implemented Features) is available.
chpp should not be used for
chpp should, due to its nature, not be used for
chpp is not a
fast program. However, this may change in the future
(see section Planned but not yet Implemented Features).
We are planning to change chpp's dynamic scoping to a lexical
scoping scheme. Furthermore, we want to introduce references
(i.e. pointers) to the language, which also implies the need for garbage
collection. These two features would not only make chpp a cleaner
language but should also open the possibility of making the chpp
interpreter a lot faster.
We would also like to add a few extension packages to chpp, which
will make it more suitable for and easier to apply to various
applications, most notably CGI scripting, HTML generation and database
interfacing.
chpp
chpp is available for free download on the world-wide-web. Point
your web-browser at @url{http://chakotay.ml.org/} (or
@url{http://chakotay.ml.org/chpp/} if you are using an ancient
browser). From there you can download the latest version of chpp.
chppNot much here, yet.
chpp is far from error-free in its current version. It works
quite reliably now when not stressed too far, though. The biggest
problem is currently that chpp's error handling is
insufficient. chpp does not report some errors, while others
cause it to crash or to end up in an endless loop. We do of course
plan to change this in the future.
Before you tell us about a bug, please check that you are using the
latest version of chpp (see section Obtaining chpp). If this is not
the case, please upgrade and try again.
Please do not report bugs that concern chpp's error handling. We
know that it is unreliable and buggy and will change that. You should,
however, report any incident where chpp does anything wrong with
a script which you believe is correct. In such a case, please write us
an email containing the script that causes chpp to fail and any
additional files that your script needs. Better yet, try to narrow the
bug down to the smallest script possible. Do also include information on
the configuration you ran chpp on, especially if the bug only
happens to show up with this configuration. The email address you should
send your bug-report to is @email{chpp@unix.cslab.tuwien.ac.at}.
chpp is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
chpp is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with chpp; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
chpp was designed and implemented by Heinz Deinhart and Mark
Probst. Check out the chpp homepage (see section Obtaining chpp) for
more information.
Our thanks go to Tatjana Svizensky for proofreading this manual and to Herbert P@"otzl for donating the hash-table functions, which we were too lazy, erm, too busy to implement, and for not reading the examples chapter of this document.
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